Two types of cartridges for the containing of coffee powder are substantially widespread on the market: rigid cartridges and semi-rigid cartridges.
Rigid cartridges, having a substantially cylindrical or truncated cone shape, comprise two components in rigid plastic material heat-sealed or welded, with ultrasounds one in relation to the other. Placed inside the cartridge are the coffee powder and a filter in contact with the wall of the cartridge on the beverage output side.
Generally at least the wall of the cartridge on the water input side and possibly also that on the beverage output side is perforated. In this way, when the cartridge is inserted in an apparatus for the extraction of beverages, on the perforated input wall hot pressurised water is injected, which, traversing the powdered product inside the cartridge, retains the flavours so as to generate the beverage, which is dispensed on the output side of the cartridge.
This type of rigid cartridge has the disadvantage of the product in its interior being exposed to the outside environment, so that it requires a further hermetic packaging in order to preserve the product from contact with the outside.
This entails an additional cost of packaging.
Semi-rigid cartridges comprise a cylindrical or truncated cone container of reduced thickness, for example in aluminium, which after being filled with powdered product is closed with a breakable membrane, in such a way that the product is hermetically sealed inside the flexible cartridge.
When the semi-rigid cartridge is inserted in the apparatus for the extraction of beverages, a punch perforates a wall of the cartridge to allow the entry of hot water into the product for the formation of the beverage which is dispensed from the opposite wall, which is also perforated generally by means of an additional punch or a plate of the apparatus.
Such a semi-rigid sealed cartridge does not need an additional casing in order to preserve the flavour of the product.
However the sudden breakage of the walls of the cartridge does not allow an optimal retaining of the liquid inside the cartridge, and therefore the obtaining of a beverage of good quality.
WO2010/137952 describes a capsule for the containing of powdered products for the preparation of beverages, comprising a substantially rigid circumferential wall, closed below and above by means of a layer of filter in woven or nonwoven fibrous material. Said filter layers are perforated with mechanical means in order to allow the passage of the fluid.
U.S. Pat. No. 5,656,311 describes a capsule suitable for containing a powdered product for the production of beverages comprising a container body provided with a base, a lateral wall and an upper flange provided with a lip whereon a closure membrane is applied, provided with zones of lesser thickness suitable for facilitating the breakage thereof, which takes place by means of a tool suitable for perforating both the upper face and the lower face of the capsule.
WO 2010/063644 describes a capsule containing powdered product for the preparation of beverages by means of the passage of a liquid through said product using centrifugal forces. The capsule comprises a containing body with an open surface whereon a closure membrane is applied having a central portion and a peripheral portion suitable for being perforated by mechanical perforation means, in order to allow the input of the liquid and the output of the beverage from the capsule respectively.